Point-Of-Sale (POS) devices often include a variety of integrated devices, such as scanners, scales, integrated scanners with scales, card readers with on-screen signature capabilities, and the like.
A scale (of integrated scanner with scale) in a typical installation often experiences mechanical vibrations coming from the operational environment. For example, at a check-station (type of POS device), product take-away belts and motorized turntables are both common and troublesome sources of mechanical vibrations. Mechanical vibrations affect the operation of a weigh scale, such that a measured weight fluctuates in value in response to the vibrations. These weight fluctuations can result in slow scale settling performance, no scale settling, scale underweight issues, and incorrect weight issues.
Mechanical vibrations encountered in the typical operational environment of a scanner/scale may be broadly characterized as have two different flavors: periodic; and, aperiodic. The most aperiodic vibrations happen as a result of customer and cashier activity during the check-out process. Placing an item on the weigh-plate and taking an item off of the weigh-plate are two significant sources of aperiodic vibrations. Aperiodic vibrations are both intermittent and unpredictable in the timing of their occurrence and can be properly viewed as a necessary part of the interaction between customer, cashier, and the POS equipment. Aperiodic vibrations also have the property that they decrease in intensity while the cashier and customer are waiting for the scale to determine the stable weight of an item just placed on the weigh-plate. As such, aperiodic vibrations associated with customer and cashier activity are not significant source of problems in weigh scale operation.
In contrast, the majority of periodic mechanical vibrations come primarily from mechanical conduction of motor vibrations from various sources within the environment. Example sources of periodic mechanical vibrations in a POS check-out station are the powered belts that move product to the cashier and then move product away from the cashier. Both motors and gear trains produce vibrational frequencies related to the rotation speed of their various components. Depending on the design of the check-out station, those vibrational frequencies can be felt by the scanner/scale and may even be amplified by the mechanical coupling between the installed weigh scale and the check-out station. While a scanner/scale cannot be expected to predict the kind of vibrational environment into which it may be installed, once it is installed, the vibrational environment takes on a much more predicable characteristic. When a scale is used in such an environment there is a need to have a scale that has some immunity to or makes some adjustments to account for vibrations encountered in its specific environment.